Delay or oscillating circuits



g- 1957 c. E. ATKINS ETAL 3,334,278

DELAY OR OSCILLATING CIRCUITS Filed June 5, 1964 INVENTORS United States Patent 3,334,278 I DELAY OR OSCILLATING CIRCUITS Carl E. Atkins, Montclair, and Robert L. Ziolkowski,

Plainfield, N.J., assignors 'to Wagner Electric Corporation, a corporation of Delaware Filed June 3, 1964, Ser. No. 372,335 8 Claims. (Cl. 317-141) ABSTRACT OF THE DISCLOSURE A time delay circuit is described employing a semiconductor diode, a heater and a relay. The diode is reversely connected so that it conducts no current at room temperature. When the diode is heated, it breaks down and conducts current so as to shunt the relay winding and thereby deenergize the relay. The action of the relay armature is used to control other circuits.

The present invention relates to delay and oscillating circuits, primarily those employing relays, and provides such circuits which have long periods of delay and oscillation, respectively.

In accordance with the present invention long period delay and low frequency oscillating circuits are provided which are compact, simple, reliable, very inexpensive and readily adjustable. Generally speaking, each of these circuits has an energization circuit including a back-biased diode with a heater coil wrapped around it for heating the diode to change the diodes reverse resistance. In operation of the particular delay or oscillating circuit, the period of the delay or oscillation is controlled by the change in current flow through the diode caused by the change in the diodes reverse resistance due to heating the diode with heat from the heater coil. Since the rate at which the diode is heated by the heater coil is determined by the magnitude of the current flow through the heater coil, this means that the desired period of delay or oscillation in the operation of the circuit can be set by control of the current flow through the he ater coil.

For a better understanding of the present invention and the particular novel features thereof reference should be had to the accompanying claims and to the following description of two embodiments 'of the invention which should be read while referring to the accompanying figures of which:

FIG. 1 is aschematic diagram of a delay circuit which will switch into one state upon pressing a button and will automatically switch back to its initial state after a selectable period of time; and

FIG. 2 is a schematic diagram of an electromechanical oscillator. 1

In the embodiment of the invention shown in FIG. 1, the coil 10 of a relay 11 is connected between a normally open contact 12 of the relay and the positive terminal 14 of a 12 v. DC supply in .series with a lamp bulb 16 and a resistor 18. The armature 20 of the relay 11 associated with this normally open contact 12 is connected to the grounded terminal 22 of the 12 v. DC supply and is normally positioned against a contact 24 which is connected to one arm 26 of a two arm push buttonswitch 28. When the push button 28 is depressed this arm 26 contacts a normally open terminal 29 of the switch 28 which is connected to the normally open contact 12 of the relay.

The second arm 30 of the push button 28 is connected to one side of the resistor 18. When the push button is depressed this second arm 30 contacts a second normally open terminal 32 of the switch 28 which is connected to the other side of the resistor 18. Therefore, when the push button 28 is depressed current will flow from the positive 3,334,278 Patented Aug. 1, 1967 terminal 14 through the lamp 16, the arm 30 of the push button 28, coil 10 of the relay, the arm 26 of the push button 28, the contact '24 and the armature 20 of the relay to the grounded terminal 22. This current flow energizes the relay 11 causing the armature 20 to move away from contact 24 and against normally open contact 12, so that current flows through the normally open contact 12 and the armature 20 of the relay to the grounded terminal 22 instead of through arm 26 of the push button 28 and contact 24 and the armature 20 of the relay.

When pressure is taken off the push button 28 the arms 30 and 26 move away from the contacts 32 and 29. However, the relay 11 remains energized because current flow from the positive terminal 14 through the lamp 16, resistor 18, the coil 10, the normally open contact 12 and the armature 20 of the relay to the grounded terminal .22 of the supply is suflicient to maintain energization of the relay 11.

Connected in shunt with the coil of the relay is a semiconductor diode 34 which is back-biased by the potential across the coil 10 of the relay 11. Wrapped around the diode is a heater coil 36 and the heater coil and the diode are set in a heat conducting material 38 for maximum heat transference from the coil 36 to the diode 34. The heater coil 36 is connected, across the lamp 16, the resistor 18 and the coil 10 of the relay, in series with a variable resistor 40. Therefore, before the push button was depressed the heater coil did not heat the diode because the circuit through the heater coil 36 between the terminals 14 and 22 was incomplete. However, when the relay is energized and the armature 20 is against the contact 12, the heater coil is connected across the terminals 14 and 22 in series with the variable resistor 40. Thus current flows through the heater coil and starts heating up diode 34. As the diode heats up it finally reaches a point where it breaks down in its backward direction allowing current to flow freely through the diode in the reverse direction. This means that current will now flow through the lamp 16, the resistor 18, the diode 34 and the normally open contact 12 and armature 20 of the relay to the grounded terminal 22, bypassing the coil 10 of the relay. This current flow through the diode 34 is sufficient to deenergize the relay 11, thus causing the armature 20 to fall away from the normally open contact 12 and against the normally closed contact 24. This means that the circuit across the coil 10 and the heater 36 is broken since the arm 26 of the push button 28 does not complete the circuit through contact 24 to ground unless the push button is depressed. Thus the relay 11 remains deenergized and current no longer flows through the heater .36 so that the diode 34 starts cooling to return the circuit of FIG- URE 1 to its initial condition.

The length of time the relay 11 remains energized is determined by the magnitudeof the current flow through the heater coil which in turn is determined by the setting of the variable resistor 40. In one application, the length of time for which the relay 11 remains energized can be changed from approximately 21 seconds to 1 minute and 40 seconds by changing the position of-the variable resistor 40 from its minimum setting to its maximum setting.

The purpose of the lamp 16, the resistor 18 and another resistor 44 which are connected across resistor 18 and the coil 10 is to obtain a difference in thecurrent flow through the coil 10 which will expedite energization of the relay and at the same time make the deenergization of the relay relatively easy.

When the push button 28 is first depressed the lamp 16 is cold and therefore its resistance is low. At the same time the armature 30 shunt-s resistor 18 so that for all practical purposes the coil 10 is connected directly across the 12 v. DC supply. This means that it receives a maximum energization current. However, when the push button 28 is no longer depressed resistor 18 is again inserted in series with the coil 10. Also as current flows through it, lamp 16 heats up and its resistance increases. Both the addition of resistor 18 into the energization path and the increase in resistance of the lamp 16 decreases current flow through coil 10. With this decreased current flow through coil 10, the change in current through the coil necessary to deenergize the relay 11 is smaller than would be necessary to deenergize the relay right after it has been energized and is receiving maximum energization current.

As shown, a second set of contacts 46 may be employed to control current flow to devices as a function of the energization and deenergization of the coil Referring to FIG. 2, a lamp 48, a diode 50 and the coil 52 of a relay 54 are connected in series between the positive and grounded terminals of the 12 v. DC supply. The diode 50 is back-biased by this supply so that current cannot flow therethrough and through the coil 52 of the relay to energize the relay 54, thus the relay normally is unenergized. Also connected between the positive and ground terminals to the 12 v. DC supply is a series circuit including a heater coil 56 which is wrapped around the diode 50, a variable resistor 58, a normally open switch 60, an armature 62 of the relay 54 and the normally closed contact 64 of that armature.

When the switch 60 is closed it means that current will flow through the heater coil 56 between the positive and negative terminals, heating the diode 50. Eventually, as is the case of the circuit in FIG. 1, the=diode is heated sufficiently so that it breaks down in its reverse direction, allowing current to flow through it, the lamp 48, and the coil of the relay 54, energizing the relay. With the relay energized it attracts the armature 62 away from the normally closed contact 64 and-towards a normally open contact 66, thus breaking the energization circuit for the heater 56, so that current can no longer flow through heater 56. This means that the heater 56 will start cooling allowing the diode 50 to cool and cut oil the current flow through the coil 52 of the relay, deenergizi ng the relay. This completes the circuit through the heater 56 starting another cycle as described above. It can be seen that with this circuit the relay will alternatively be energized and deenergized as the electric circuit through the heater 56 is alternatively made and broken by the energization and deenergization of the relay with the result that this circuit functions as an electromechanical oscillator.

As in the case of circuit of FIG. 1, the lamp 48 aids in deenergizing the relay by heating up and cutting down the current flow through the coil 52 once the relay is energized.

The period of oscillation can be controlled by resistor 58 since this resistor determines the magnitude of the current flowing through the heater 56 and thus determines the length of time it takes to heat the diode until it breaks down. When it is desired to stop the oscillation of the armature 62 between contacts 64 and 66, all that isnecessary is to permanently break the circuit through the heater by reopening the switch so that once the diode cools, oscillation will stop.

A second set of contacts 70 is provided for controlling the current flow through a circuit as a function of the oscillation of the energization and the deenergization of the coil of the relay 52.

Above two embodiments of the present invention have been described. However, it should be apparent to.those skilled in the art that variations and modifications in the above described embodiments can be made without departing from the spirit and scopeof the invention. Therefore, it will be understood that this covers all modifications and changes of the above described embodiments which do not depart in spirit and scope from the above described invention as embodied in the appended claims.

What is claimed is:

1. A time delay circuit comprising:

(1) a source of direct current potential,

(2) a relay including a winding, at least two normally open contacts, and at least two normally closed contacts,

(3) an operating circuit for energizing said relay and latching it in its operated condition,

(4) a semiconductor diode connected in parallel with said winding and poled so as to be nonconductive, and

(5) an electrical heater for said diode, whereby the actuation of said relay closes the normally open pair of contacts and applies current to the heater to render said diode conductive after a predetermined time interval, thereby shunting said winding and de-energizing said relay.

2. The time delay circuit of claim 1 including a variable resistor connected in series with the electrical heater to vary the time interval during which the relay remains energized.

3. A time delay circuit according to claim 1 wherein said operating circuit includes ganged switching means which, when momentarily closed, is operative to momentarily energize said winding of said relay, thereby closing a series path from the power source through said winding and an armature of said relay to ground.

4. A time delay circuit according to claim 1 wherein said ganged switching means are actuated by pushbutton means.

5. A time delay circuit according to claim 1 wherein said circuit includes a non-linear resistance element in series with said winding of said relay.

6. An electromechanical oscillator comprising:

(1) a power source;

(2) a relay having at least one armature, a winding and at least one contact associated with each armature;

(3) an energizing circuit for said relay including;

(a) a solid-state diode connected in series with said winding;

(b) heating means associated with said diode and connected in series between said power source and a normally closed contact of said relay, and

' through the armature of said relay to ground;

(c) switching means connected in series between said heating means and said normally closed contact.

7. The electromechanical oscillator of claim 6 wherein a variable resistance is connected in series between said heating means and said switching means.

- 8. The electromechanical oscillator of claim 6 wherein a non-linear resistance is connected in series between said power source and said diode.

References Cited UNITED STATES PATENTS 2,340,502 2/ 1944 Baker.

2,471,457 5/1949 Shepard 317132 X 2,718,951 9/1955 Mason.

3,166,680, 1/1965 Kevane et al. 307-88.5

MILTON o. HIRSHFIELD, Primary Examiner. L. T. HIX, Assistant Examiner. 

1. A TIME DELAY CIRCUIT COMPRISING: (1) A SOURCE OF DIRECT CURRENT POTENTIAL, (2) A RELAY INCLUDING A WINDING, AT LEAST TWO NORMALLY OPEN CONTACTS, AND AT LEAST TWO NORMALLY CLOSED CONTACTS, (3) AN OPERATING CIRCUIT FOR ENERGIZING SAID RELAY AND LATCHING IT IN ITS OPERATED CONDITION, (4) A SEMICONDUCTOR DIODE CONNECTED IN PARALLEL WITH SAID WINDING AND POLED SO AS TO BE NONCONDUCTIVE AND (5) AN ELECTRICAL HEATER FOR SAID DIODE, WHEREBY THE ACTUATION OF SAID RELAY CLOSES THE NORMALLY OPEN PAIR OF CONTACTS AND APPLIES CURRENT TO THE HEATER TO RENDER SAID DIODE CONDUCTIVE AFTER A PREDETERMINED TIME INTERVAL, THEREBY SHUNTING SAID WINDING AND DE-ENERGIZING SAID RELAY,
 6. AN ELECTROMECHANICAL OSCILLATOR COMPRISING: (1) A POWER SOURCE; (2) A RELAY HAVING AT LEAST ONE ARMATURE, A WINDING AND AT LEAST ONE CONTACT ASSOCIATED WITH EACH ARMATURE; (3) AN ENERGIZING CIRCUIT FOR SAID RELAY INCLUDING; (A) A SOLID-STATE DIODE CONNECTED IN SERIES WITH SAID WINDING; (B) HEATING MEANS ASSOCIATED WITH SAID DIODE AND CONNECTED IN SERIES BETWEEN SAID POWER SOURCE AND A NORMALLY CLOSED CONTACT OF SAID RELAY, AND THROUGH THE ARMATURE OF SAID RELAY TO GROUND; (C) SWITCHING MEANS CONNECTED IN SERIES BETWEEN SAID HEATING MEANS AND SAID NORMALLY CLOSED CONTACT. 